Improved electro-magnetic burglar-alarm



2 Sheets-Sheet 1.

E. O. CLAY. BURGLAR ALARM.

No. 25,950. Patented Nov 1, 1859.

a mum) i e E F 2 Sheets,Sheet 2.

E. G. CLAY. BURGLAR ALARM.

No. 25,950. Patented Nov. 1, 1859.

UNITED STATES PATENT OFFICE.

EDWARD O. CLAY, OF MALDEN, MASSACHUSETTS.

IMPROVED ELECTRO-MAGNETIC BU RG LAR-ALARM.

Specification forming part of Letters Patent No. 25,950, dated November 1, I859.

act as to enable those skilledin the art to practice my invention.

My invention relates. to an improved mode of giving notice of the entrance of a burglar into a building through a door or window, and of indicating the place of entrance; and these objects are effected by the use of a closed electric circuit, a galvanometer, and a hell with the proper mechanism for ringing it, so

"arranged that'rhe opening of a door or window will break the circuit for a moment andset the bell to ringing, and immediately close it again through a new path or coil of wire, which offers an increased resistance to the current and causes the needle of the galvanom eter to point to a figure on the dial ,whi'ch indicates the point where break was made.

Figure 1 in the drawings is a perspective view of the windows and'deor of a room connected by the circuit with the indicator and alarm apparatus. The latter are generally placed in another room, and the doors and windows may belongto difi'erent rooms. Fig. 2 represents a window partially raised, so as to cause a break in the circuit. Fig. 3repre- 'sents a window fully opened, and shows how the circuit after being broken is reestablished. through a 'coil of wire, which Icall a resist-- ance-coil, for the purpose of deflecting the needle-to the number on the dial indicating the point of attack. Fig. 4. shows the indicator and alarm apparatus with a coil of wire, which I call a f regulating-coil, the object of which is to regulate the strength of the current. The same letters in the several figures refer to corresponding parts.

A A .in Fig. 1 represent the floor of the room; B B, the side of a house or room con taining the two, windows marked 1 and 3 and the door marked 2.- These parts of a house are sufiicient .to illustrate the operation of my invention arid exhibit its construction.

T reptre cuts the table or shelf on which the bell app the indicator, and the regulating-coil are {Ell d, and it may be in any part of the buildir be guarded, or in another.

H H represen h ell apparatus, containing a bell and harm weight or spring as a motive power, a trai h el-work for operating the hammer, and fly-wheel or other regulator for regulating the movement of the net, M, an armature,Y, and a spring, K, the object of all which will be explained hereinafter. U

W W W W. represent the wire which iconstitutes a part-of the electric circuit. It is connected with the screw-cups N and P, which are, in turn, connected with the opposite poles of a battery. The needle of the galvanometer or indicator is represented by s It, the dial by d, and the figures 1 2 3 on the dial indicate the points to which the needle should point when adoor or window is opened. This part of the apparatus may be constructed in a variety of forms. It differs from the galvanometer as ordinarily employed for measuring the strength of a current in having the numbers on the dial so placed that with acnrrent of a given strength the needle shall be deflected to a particular figure when the current meets a certain resistance by passing through a given. resistance coil. Its office is not to measure the strength of the current, but to indicate by means of the varying strength of the current the point where adincreased resistance is introduced. In the galvanometer represented in the figure the current passes through a coil of wire'finf-v should he maintained at a constant strength, which is indicated-by the needle standing at zero, when the current is passing through none of the resistance-coils, but is" traversing its shortest path; but as the action of .the battery, and consequently the strength of the current, are constantly changing, it isnecee sary to provide some means for controllingthe current and increasing or diminishing its strength to meet the varying conditionsof the battery. This Ido by-meaus of theregulatwheel-work. It also exhibits an electromagdicated by the perpendicular black lines) in.

,In order thatthe indications should be corin g-coil J). This coil is placed near the indicator, and is composed of fine insulated wire, with branches leading off, so that more or'lcss of the coil will be embraced in the circuitand more or less resistance ofiered accordingly as the circuit; is completed through one or the other of the branches, Each of these branches is connected with one of a row of pins standing inthe arc'of a circle, the tops of which are filed flat and are in the same plane or level, so that the switch or lever to t, in moving about on its pivot 21, shall come in contact with the top of each pin. The circuit is connected with the pivot a and the switch w t, and also with the pins, and through these more or less of the coil can be embraced in the circuit at the will of the operator or person having charge of the apparatus.

If it is found that the needle of the indicator is deflected beyond the zero point when none of the resistance-coils are brought into the circuit, it shows that the current is too strong, and the switch must be moved till the needle stands at the zero-point, and so on in like manner if the needle fails to reach the zero point, the current being too weak.

The form of battery best adapted to this apparatus is that known as the Smee battery; but it is necessary to adjust the apparatus to a certain number of cells or elements, and to always employ that number.

The devices for causing an alarm to be rung and the proper indications to be given are represented at the'side of each window and over the door.

It will be observed that when the windows and the door are closed the circuit is completed directly through the bent levers b a o and b a ,c at the windows and the spring b, a, or s at the door, these levers and springs belng held in contact with the metallic plates 1) p. p

by the pins n, n, and n in the door and win dows, and in this situation the resistance-coils k, k, and k are not brought into the circuit.

, The resistance-coils are connected with the main circuit at at, m and w, and when the windows are opened the springs s and s draw away from the plates 1) and p", the bent levers b a c and b a" c, and press them against the pins 13 and i", which are connected with the resistance-coils k and k, and through which the circuit is now established. The springs s and s", it will be observed, constitute a part of the circuit. In the same manner,when the door is opened the spring b,c, or s is relieved from the pressure of the pin a and springs back fromthe plate or pin till it reaches a pointprojectiug from the plate '5, when the curirlecnt is established through the resistancecoi The ends 0 and c of the bent levers at the window may, if desired, be made so short that when drawn upward by the springs the pins n and n will pass them in descending and not break the connection with the coils k and 74; but if the levers are pressed down by hand before the windows are closed the ends a and 0 down by them. The same object will be easily attained at the door, and the object of such an arrangement would be to maintain the needle of the indicator at the proper point it a burglar should hastily eflect an entrance and close the door or window after him.

The devices above described for breaking the circuit and transferring the current from one branch of a circuit to another containing a greater resistance may be called, for convenience, a switch, and its form and construction may be greatly varied without substantially changing its mode of operation. Its essential condition is that by the opening of a door or window it shall break the current,

for a. moment, and then transfer it to another branch of the circuit.

Thebell mechanism or clock-work for ring ing the hell or giving an alarm may'be constructed in a variety of forms also. The essential elements are a spring, weight, or other suitable motive power connected with a train of wheel-work so arranged that a hammer shall be made to strike the bell rapidly. It is connected with the circuit as follows: Uonnected with the clock-work is an electro-magnet, M, the coil of which forms a part of the circuit. An armature, Y, is attached to one end of a lever pivoted at m. The other end of the lever carries a detent, which engages with fly-wheel r of the clock-work, or with some other part of the machinery, so as to arrest its action while the armature Y is drawn into contact with the poles of the magnet. The upper end of the lever is connected with a spiral spring, K, which tends todraw back the armature; but its force must be soadjusted in'respect to the force of the current that when the armature is placed in actual contact with the poles of the magnet it will be held there by the force of the current, but when the armature is withdrawn from the magnet the force of the spring shall be sutficient to retain it in opposition to the force of the current. By this arrangement it will be seen that if the clock is wound up readyfor action and the armature Y is placed in contact with the magnet, the circuit being closed, it will be held there and the machinery will be held in check; but if the circuit is broken the armature will be drawn back and the machinery released, so that an alarm will be given, and it the circuit is immediately closed the alarm will, notwithstand ing, continue, because the force of the magnet will notbe suflicient to draw the armature into contact with its poles, and thus arrest the action of the machinery.

The tensionof the spring may be regulated by a screw in the well-known manner.

It should be observed that in constructing this apparatus the battery should be such that the needle of the galvanometer will stand at zero when about one-half .of the regulatingcoil is brought into the circuit and all the resistance-coils are excluded, and in this situation the resistance-coils are to be successively will come into the path of the pins and be kept brought into the circuit, and the position of the needle is then to be marked on the dial and the point indicated by the numbers of the r0031 or door or window where the coil is situate The operation of my invention is as follows: The several windows and doors to be guarded being shut and the circuit closed, the switch to tis moved to a position in which the needle of the galvanometer shall stand'at zero, the clock is wound up, and the armature Y is placed in contact with the poles of the magnet. In this position of the apparatus it is ready to give an alarm. If new a window is raised-for instance, the one markedv 3" in the drawings-the springs will move the bent lever or switch 0 a b away from the plate into contact with the pin t, and the current will be di rected through the coil k. While the arm b of the lever is moving over the interval between 1) and'i the current will be interrupted, and the magnet M being demagnetized, the armature Y will be drawn back by the spring -K and the bell will commence ringing. When the arm of the lever comes into contact with the pint the circuit is again closed through the coil k, and the needle of the ga'lvanometer: will point to 3on the dial,and a person alarmed by the ringing of thebell can, at a glance, discover the source of the alarm by looking at the dial. It is also apparent that the armatureY will be released and an alarm given whenever the circuit is broken at any point orthe current suspended from any cause, as well as when a burglar attempts to efl'cct an entrance, and thus the apparatus gives notice of any disarrangement in its condition which interrupts the current.

Having fully described my invention, what I claim is- 1. The combination in an electric burglaralarm, of a gal vanometer with a resistance-coil and an automatic switch, for the purpose of indicating the point where a burglar is attempting to efl'eet an entrance, substantially as herein described.

2. The combination, in an electric burglaralarm, of a galvanometer and a bell with suitable mechanism for ringing it, for the purpose of simultaneously giving an alarm and of indicating the place of attack.

3. The use, in a burglar-alarm, of a regulating-coil, in combination with the resistancecoils, substantially as herein described, for the purpose of maintaining a constant relation between the strength of the current and the varying resistances of the circuit when the respective resistance-coils are included.

. EDWARD O, CLAY.

Witnesses:

J. B. CROSBY, FRANUIS GOULD. 

